In the technology field of mechanism or in daily life, mounting or dismounting components is very common. The patent application with the application number of CN200610058779.8 and the title of “a spanner with swinging head and button structure” published on Mar. 14, 2007 that, the button structure of the spanner comprises a handle, a swinging head and a button; the handle comprises a first end and a second end; the first end is a turning portion, and the second part is provided with a pivot portion; the button is pivotally connected on the abdominal region of the swinging head and can make the swinging head swing pivotally, but the angles of the handle cannot be changed, and the handle cannot be turned quickly. The patent application with the application number of CN200510015991.1 and the title of “positioning structure for head pivotal swinging of a spanner” published on May 17, 2007 that, the working head can be positioned at any angles required; two working heads can even be realized, but the handle is not convenient for turning rapidly; what's more, two ends of the whole tool cannot be folded, so the spanner is too long to store easily; if the length of the rotating rod of the spanner is reduced, the spanner will be easy to store, but the long moment arm of force which is convenient for holding and rotating can no longer be obtained. The American patent application with the publication number of US20100154604 discloses a tool with adjustable working angle, as shown in a stereogram of the prior art in FIG. 1, the tool comprises a first rod, a second rod and a connecting member provided at both ends thereof with a first connecting portion and a second connecting portion; the first connecting portion is pivotally connected between the first clamping portions of the first rod, and the second connecting portion are pivotally connected between the two second clamping portions of the second rod; the head of the tool is provided at the other end of the second rod. As shown in a schematic diagram of the prior art in FIG. 2, when the tool is in the limiting position, the first rod and the second rod of the connecting member are approximately perpendicular to each other, therefore, a user needs to substantively swing his/her arm when mounting or dismounting components. The tool is time-consuming and laborious and has low efficiency in mounting or dismounting components.